What Is the Renal Cortex?

A diagram of a kidney, including the renal cortex.
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  • Written By: Dulce Corazon
  • Edited By: C. Wilborn
  • Last Modified Date: 15 April 2014
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The renal cortex is part of the kidneys containing mostly nephrons and blood vessels. Its function is to filter the blood and remove waste products inside the body. Nephrons are the basic functional units of the kidneys, with each kidney having one million or more of these important structures. In each nephron, there is a glomerulus and a renal tubule, which is divided into sections. The renal tubule is a long tube that winds through both the renal cortex and the renal medulla, a number of triangle-shaped structures in the kidney.

The different parts of the kidney — the renal cortex, the renal medulla, and the renal capsule — can each be identified by their appearance and color. The renal capsule is a transparent membrane that lines the outer part of the kidneys and acts as protection against infection and injury. Located on the inner part of the kidneys, the medulla is darker in color and contains eight or more triangular structures known as the renal pyramids. Located between the capsule and the medulla, the cortex can be identified by its paler color. It also extends down between the pyramids of the kidneys.

Each part of the kidney contributes to the elimination of waste and formation of urine inside the body. Blood vessels deliver blood from the body towards the kidneys. As blood passes through the renal cortex, the glomerulus filters it to remove waste products before returning the blood to circulation.


The filtrate containing waste products then passes through the sections of the renal tubules, where reabsorption and secretion of important substances take place. Sections of the renal tubule found in the cortex are the proximal tubule, the distal convoluted tubule, and portions of the collecting ducts, while the renal medulla contains the Loop of Henle and other portions of the collecting ducts. Urine, the final product, then passes through the ureter down to the bladder for excretion.

Many diseases can affect the structure and functions of the renal cortex in one or both kidneys. Infections, autoimmune disease, cancer, and heart disease are some factors which affect the formation and elimination of urine. The glumerulus is commonly susceptible to infections and injury from autoimmune disorders. Radioactive dyes and some drugs can also be toxic to the tubules.

All parts of of the kidneys can be viewed through the use of an abdominal ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI) studies. Laboratory blood tests and urinalysis are also used to evaluate the functions of the kidneys. A renal biopsy is sometimes done to study the structures in these organs and as an aid in the diagnosis of kidney disease.


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Post 3

I would normally think that a cortex has something to do with the brain, but it actually just comes from a Latin root meaning "bark." It is the outer layer of an organ, and is usually folded or textured, somewhat like tree bark.

Post 2

Kidney stones can be the most painful naturally occuring body function to some people. Men describe it as the nearest they've ever come to giving birth. This issue is a result of buildup in the kidneys over the course of a long period of time and usually doesn't occur until after your forties. There are many instances of it occurring earlier than that, however.

Post 1

i want to ask what is the difference between the color of outer layer, i.e., renal cortex and the inner renal medulla.

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